The aim of this study is to assess the efficacy and safety of budesonide compared to placebo in patients with active Crohn's disease affecting the ileum and/or the ascending colon. Approximately 200 patients nationwide will be randomized to 4.5 or 9 mg controlled ileal release capsules once or twice a day, or placebo. Budesonide is a glucocortisosteroid with high topical antiinflammatory activity and significant first-pass metablism. The primary efficacy variable will be the Crohn's Disease Activity Index remission rate.